This proposal is concerned with the effects of adriamycin (ADR) and BCNU on the human lymphoblastic leukemia cell line CCFR-CEM. In particular, the cytotoxicity of these drugs for this cell line will be determined and correlated with the effects that these agents have on glutathione metabolism. It has been postulated that adriamycin acts through the production of free radicals, superoxide anions and lipid peroxides which cause DNA strand breakage and peroxidation of other cellular components. At the same time ADR inhibits glutathione peroxidase, the mjaor defense against lipid peroxides. I will explore the production of peroxides through measurement of formate oxidation and generation of malondialdehyde and determine the effects of ADR on glutathione peroxidase, glutathione (GSH) and oxidized glutathione (GSSG) and correlate these measurements with cytotoxicity. I will determine whether selenium loading will effect cytotoxicity and glutathione peroxidase inhibition. In addition, quenchers of free radicals and singlet oxygen, such as tocopherol, mannitol and carotene will be evaluated, as will superoxide dismutase, N-acetyl cystein and drugs which have been reported to block ADR uptake into cardiac tissue, digoxin and propranolol. The cytotoxicity of BCNU for this cell line will also be tested. It has been suggested that BCNU action may be related to to inhibition of glutathione reductase. Enzyme activity will be correlated with cell kill. Enzyme activity will be manipulated by addition of riboflavin or riboflavin antagonists to the medium. The reported synergism of ADR and BCNU for cytotoxicity will be explored in this system and correlated with alterations in glutathione metabolism.